Method of applying processing liquors to textile materials and apparatus therefor

ABSTRACT

A method for impregnating fibrous materials with processing liquors, such as dye liquors, comprising the steps of (1) subjecting the fibrous material to a subatmospheric pressure, (2) bringing the processing liquor and the fibrous material into mutual contact, (3) restoring the pressure on the material to atmospheric pressure. An apparatus for performing the method having an evacuation chamber for the fibrous material, means for bringing the processing liquor and the material into mutual contact and means for restoring the pressure on the material to atmospheric pressure.

United States Patent Fox et a1.

[54] METHOD OF APPLYING PROCESSING LIQUORS TO TEXTILE MATERIALS AND APPARATUS THEREFOR Inventors: Maurice Rayner Fox; Neil David Stewart;

Alfred Peter Lockett, all of Manchester, England Imperial Chemical Industries Limited, London, England Filed: a. 9, 1967 Appl. No.: 673,647

[73] Assignee:

[] Foreign Application Priority Data Oct. 10, 1966 Great Britain ..45,197/66 U.S.Cl ..I17/6l, 8/147, 8/151, 117/65.2, 117/115, 117/119, 118/50 Int. Cl. ..D06p 7/00 FieldoiSearch ..1l8/50;117/l19,1l5,61,65.2, 1l7/115;8/151, 151.1, 151.2, 152, 1, 176, 54.2,

References Cited UNITED STATES PATENTS 1,411,786 4/1922 Hopkinson ..117/61 X 1,595,486 8/1926 Minton ..1 17/61 1,742,568 1/1930 Addy ..1 17/61 X Feb. 22, 1972 2,005,637 6/1935 Schidrowitz ..1 17/61 X 3,160,896 12/1964 Smith ..8/l76 X 3,418,065 12/1968 Blount ..8/176 1,729,056 9/1929 Texler ..1 18/50 2,125,364 8/1938 Waldron ..118/ 2,339,045 1/1944 Beaver et a1.. 18/50 2,410,127 10/1946 Olson et a1 ..118/50 OTHER PUBLICATIONS I1 yashchuk, Chemical Abstracts Vol. 54 No. 18 p. 8089b Apr. 25, 1960.

ll yashchuk, Tekstilnaja promyshlennost Vol. 19 No. 7 (1959) Pp. 7.

Primary Examiner-Ralph S. Kendall Attorney-Cushman, Darby & Cushman [57] ABSTRACT 5 Claims, 2 Drawing Figures METHOD OF APPLYING PROCESSING LIQUORS T TEXTILE MATERIALS AND APPARATUS THEREFOR This invention relates to a novel method whereby processing liquors may be applied to fibrous materials, and to apparatus suitable for carrying out that method.

The impregnation of fibrous materials, such as textile materials, with processing liquors, for example dye liquors, is commonly effected by means of a padding technique, in which the fibrous material is immersed in a pad trough containing the liquor and is then passed between the flexible rollers or bowls of a padding mangle to remove the excess of liquor adhering to the material, the bowls of the mangle being loaded by mechanical or hydraulic means to a pressure such that the desired pickup of liquor by the material is achieved. In order that all parts of the fibrous material shall be uniformly treated, however, it is necessary that the material is evenly impregnated with the processing liquor. With certain types of fibrous material, an even impregnation is difficult to bring about because of an inherent inability of the processing liquor to wet the fibers of the material. Since processing liquors are usually of an aqueous character, the difficulty is most frequently encountered with fibrous materials having a hydrophobic nature, such as textile materials composed of fibers which are essentially hydrophobic, for example synthetic polyester fibers, or those composed of fibers which are naturally hydrophilic but which contain natural impurities or added substances which render them hydrophobic, for example loom-state cotton fabrics. ln such cases it is necessary, in order to achieve uniform impregnation by the processing liquor, to resort to the addition of suitable wetting agents to the liquor or preferably, where this is possible, to subject the fibrous material to a preliminary treatment which converts it to its full hydrophilic state, such as a scouring treatment. These considerations are of particular significance when the processing liquor is a dye liquor, since the achievement of an even and level dyeing depends in the first place upon a uniform impregnation of the fibrous material by the dye liquor.

it has now been found that the even impregnation of a fibrous material with a processing liquor may readily be achieved by subjecting the fibrous material to a subatmospheric pressure prior to the operation of bringing the processing liquor into contact with the material, and simultaneously with that operation or immediately thereafter restoring the pressure to atmospheric pressure.

Thus according to the present invention there is provided a method for the impregnation of fibrous materials with processing liquors, comprising the steps of l) subjecting the fibrous material to a subatmospheric pressure, (2) bringing the processing liquor and the fibrous material so subjected into mutual contact, (3) restoring the pressure on the fibrous material to atmospheric pressure either simultaneously with performing step (2) or immediately thereafter.

The subatmospheric pressure to which the fibrous material is subjected may be any pressure below atmospheric pressure, but it is preferred that a pressure of cm. of mercury or less should be employed. The period of time during which the fibrous material is subjected to the subatmospheric pressure before the processing liquor is brought into contact with it may be varied as desired, but it is in practice sufficient that the pressure surrounding the material should have fallen to the desired value when the processing liquor is introduced and there is normally no advantage to be gained by subjecting the material to that pressure for any longer period.

The processing liquor may conveniently be brought into contact with the fibrous material subjected to the subatmospheric pressure by admitting the liquor to the evacuated zone within which the material is enclosed. A partial restoration of the pressure within the zone towards atmospheric pressure may take place as a result of this admission of the liquor, but this is of no consequence provided that it is ensured that the enclosing zone is not reconnected with the atmosphere until the processing liquor has come into contact with all parts of the fibrous material. Such a procedure may be regarded as a noncontinuous or batchwise operation of the method of the invention.

Alternatively the method may be operated on a continuous basis by (l) causing a length of fibrous material to move progressively through a first zone in which it is subjected to the subatmospheric pressure and then through a second zone in which it is impregnated with the processing liquor, the two zones being separated by a suitable form of seal through which the evacuated fibrous material passes and is thereby prevented from coming into contact with the atmosphere, and (2) allowing the fibrous material to regain atmospheric pressure either on entering the impregnation zone or immediately after leaving that zone.

The processing liquor may be any treatment liquor which it is desired to apply to the fibrous material, such as liquors containing preparing or finishing agents and optical brightening agents. The method of the invention is, however, particularly advantageous when the processing liquor is a dye liquor, since it facilitates the production of even and level dyeings on a wide variety of fibrous materials, some of which may, as already explained, require special preparation in order to ensure satisfactory results by the impregnation methods of the prior art.

The fibrous materials to which the method of the invention may be applied include loose fibers and filaments, textile materials such as rovings, yarns and threads, woven and knitted fabrics and nonwoven webs such as nonwoven textile fabrics and paper. The fibrous materials may be composed of natural polymeric material, for example cotton, viscose rayon, flax or wool, orv of synthetic polymeric material, for example polyamides, polyesters, polymers and copolymers of acrylonitrile, polyolefines such as polypropylene and cellulose esters, or of mixtures of such natural and synthetic polymeric material. The method of the invention is of especial value for the impregnation with aqueous processing liquors, particularly at short liquor ratios, of textile materials which are of a hydrophobic character, that is to say textile materials which are composed either of essentially hydrophobic fibers, for example synthetic polyester fibers, or of essentially hydrophilic fibers which have been rendered hydrophobic by natural impurities or by some previous treatment, such as loom-state and waterproofed fabrics. In the case of essentially hydrophobic materials, the method permits a much improved penetration of the treatingagent into the individual fibers to be achieved; thus in the dyeing process where existing padding methods may result only in surface or ring" coloration of the fibers, use of the method of the invention leads to good penetration of the dye into the interior of the fibers. In the case of fabrics which have been rendered hydrophobic by some previous treatment step, such as sizing or waterproofing, the method of the invention enables good impregnation with an aqueous processing liquor to be achieved without the necessity for removing substances deposited on the fibers during such treatment, thus avoiding time-consuming and expensive preparation of the material prior to dyeing and/or finishing. The method of the invention is also valuable for the bulk impregnation of textile materials which, although not inherently difficult to impregnate with a processing liquor, are nevertheless in such a physical form that effective penetration of the liquor to all parts of the material is mechanically hindered; such a situation arises, for example, in the dyeing of thick masses of textile material such as madeup garments, cops, cheeses and heavyweight or deeply ribbed fabrics composed of cotton, viscose rayon, linen or wool and whereas in the dyeing of such'masses by known methods there may be little penetration of the dye liquor beyond the outer surface of the material, the method of the invention permits a rapid and thorough penetration of the material to be achieved so that even the innermost parts of the mass exhibit level coloration.

Although it is to be understood that the scope of the present inventions is not limited by reference to any theory or explanation of its operation, it is believed that the following sequence of events occurs during the carrying out of the method which has been described. The application of a subatmospheric "pressure to the fibrous material causes the evacuation of air and water vapor from the lumens, interfibrillar spaces and interchain pores of fibers and from the interstices of yarns, fabrics and webs; when the fibrous material so treated is impregnated with the processing liquor and the pressure is then restored to atmospheric pressure, the processing liquor is impelled into the spaces, pores and interstices previously occupied by air and water vapor, resulting in a much improved wetting out of the fibers or fabric by the liquor which in turn leads to a more thorough impregnation of the material than can be achieved by a traditional padding process. The wetting out of the fibers or fabric is believed to occur at the moment when the impregnated material is restored to atmospheric pressure; it is in any event as essential feature of the method of the invention that the restoration of the pressure should take place either simultaneously with impregnation or as soon as possible thereafter, and always before the actual processing step, such as fixation of a dyestuff, is commenced.

After a fibrous material has been impregnated with a processing liquor according to the method of the invention it may be desirable to pass the material through a padding mangle or other conventional means for regulating the pickup of liquor. It is found, however that when operating the present method, particularly on hydrophobic textile materials, it is possible to achieve a higher percentage pickup without the risk of seepage of surplus liquor from the surface of the material than is possible using the known methods of the art; for example with a loom-state cotton fabric a pickup of as high as I percent may be possible, compared with only some 70 percent by conventional padding methods. Thus where the processing liquor is a dyeliquor, the method of the invention permits higher pickup to be employed without increasing the risk of migration of dyestuff clue to seepage or drainage and of consequent unevenness of coloration. This effect may be attributed to the improved penetration of the liquor into the interior structure of the fibers or fabrics that occurs in the present method as compared with the methods of the prior art. A further advantage of the present method, which may also be attributed to improved penetration, is that when it is employed in a dyeing process in which the textile material is subjected to an intermediate drying step after it has been impregnated with the dye liquor, there is a much reduced tendency for migration of dyestuff due to differential thermal effects during the drymg.

The pickup of processing liquor by a given fibrous material increases as the pressure to which it is subjected before impregnation decreases. Some data illustrating this effect for three different textile materials are given in the accompanying Table.

The advantages conferred by the method of the invention are not, however, wholly dependent upon achieving an increased pickup of processing liquor; thus in the case of a textile material composed wholly of a synthetic polyester, such as polyethylene terephthalate, the amount of a disperse dye liquor picked up in the present method is not significantly greater than that picked up in a conventional padding process, but the dyeings obtained are nevertheless improved in respect of both depth and levelness.

The present invention also relates to apparatus suitable for carrying out the method for applying processing liquors hereinabove described.

Thus according to a further feature of the present invention, there is provided apparatus suitable for the impregnation of fibrous materials with processing liquors, the apparatus comprising a chamber for enclosing the fibrous material, means for evacuating the chamber to a subatmospheric pressure, a reservoir for the processing liquor, means for bringing the processing liquor and the fibrous material into mutual contact and means for restoring the pressure on the textile material to atmospheric pressure either simultaneously with bringing the liquor and the material into mutual contact or immediately thereafter.

The apparatus of the invention may be suitable for carrying out the method hereinabove described by either a noncontinuous or a continuous procedure. For a noncontinuous or batchwise" procedure, the apparatus may be embodied as shown diagrammatically in FIG. 1 of the accompanying drawings.

In FIG. 1, A represents the chamber in which a textile material B is enclosed; the textile material may conveniently be batched so as to form a compact mass. The upper extremity of the chamber A is provided with a tubular arm C, having a stop-cock D whereby it may be connected at will either with the atmosphere or with a source of vacuum. The lower extremity of the chamber A carries a second arm E, having a stop-cock F, which opens into a reservoir G containing the processing liquor H. In small-scale operation, the apparatus may conveniently be constructed of glass, but for large-scale operation stainless steel is to be preferred as the constructional material.

In operating the apparatus, after the textile material has been enclosed in the chamber A, the stop-cock F is closed and the chamber is connected via the arm C to vacuum and is evacuated to a pressure of 10 cm. Hg or lower. The stop-cock D is then closed and the stop-cock F is opened, allowing the processing liquor to ascend into the chamber A. As soon as the textile material has become completely immersed in the processing liquor, stop-cock F is closed and stop-cock D is opened to the atmosphere. The pressure in the chamber A is thus returned to normal, and efficient wetting of the textile material with the processing liquor thereupon takes place. The textile material is then removed from the chamber and, if necessary, passed through a padding mangle to regulate the pickup of the processing liquor, after which it receives furthcr treatment as necessary.

For carrying out the method of the invention in a continuous manner, the apparatus may be embodied as shown diagrammatically in FIG. 2 of the accompanying drawings.

In FIG. 2, J represents the chamber which is connected by means of the side-arm K to a source of vacuum. The upper part of the chamber J is integral with a reservoir L containing the processing liquor M; the top and bottom surfaces of the chamber J are perforated by suitably shaped slots N and P through which a textile material Q may pass in a continuous length in the direction indicated by the arrows, seals R and S being provided at the slots N and P which prevent passage of the processing liquor into and/or loss of vacuum from the chamber J, but permit movement of the textile material. T represents a padding mangle which serves to impart motion to the textile material and to regulate the pickup of processing liquor. When the apparatus is in operation, the textile material passes continuously through the apparatus, entering through the slot P and seal S into the chamber J, which is maintained at the desired subatmospheric pressure. After the material has been subjected to that pressure for a suitable period of time depending on its rate of progress and the relative dimensions of the chamber J, it passes at once through the slot N and seal R into the reservoir L containing the processing liquor M. On entering the liquor, the pressure on the textile material is at once restored to atmospheric pressure (neglecting the slight excess pressure due to the head of liquor) and the material finally passes through the padding mangle T which controls the amount of processing liquor retained in it. The material is thereafter subjected to a further treatment as appropriate, such as a fixation process in the case where the processing liquor is a dye liquor.

The invention is further illustrated, but not limited, by the following Examples.

EXAMPLE 1.

1 d E71? of soda ash. As soon as the dye liquor has risen into the chamber to a sufficient height to immerse the material completely, the lower stop-cock is closed and the vacuum within the chamber is released by opening the upper stopcock. The material is then removed from the apparatus, passed through a padding mangle loaded to a predetermined extent and then batched for 2 hours. The pickup of dyeliquor 1 by the material is found to amount to 105-1 percent of the original dry weight of the material and, after soaping off unfixed dye, a level, wall-penetrated dyeing is obtained.

By way of comparison, a sample of the same loom-state cotton poplin material is padded in the same dye liquor as that described above under normal padding conditions (i.e., without the use of vacuum) with the padding mangle loaded to the same extent as before. The pickup by the material under these conditions is found to amount only to 50 percent and consists largely of dye liquor on the surface of the material; the dyeing obtained after soaping off is found to be unlevel and poorly penetrated.

EXAMPLE 2 Dyeing of Unprepared Cotton Cops A cop of cotton 6" in length and 1" in diameter is placed in the chamber of a glass apparatus of the type illustrated in FIG. 1 of the accompanying drawings. The chamber is then evacuated to a pressure of less than 0.1 cm. Hg. By opening the lower stop-cock of the apparatus there is drawn into the chamber from a reservoir a dye liquor containing 5 g./1. ofthe dyestuff having the Color Index designation C.1. Vat Green 1 (C.l.59825), 5 g./1. of sodium hydroxide flake and sufficient sodium hydrosulphite to reduce the dye completely. The cop is allowed to become completely immersed in the dye liquor, whereupon the lower stop-cock is closed, the upper stop-cock is opened so as to release the vacuum and a current of air is then drawn through the liquor and cop in order to effect oxidation of the leuco-form of the dye. The cop is removed from the chamber and is slit open; it is found that the dye liquor has penetrated to the center of the cop and that the yarn itself is well penetrated and evenly dyed throughout. H

EXAMPLE 3 Pad-steam Dyeing of Wool Serge Samples of wool serge are dyed in a dye liquor containing 10 g./l. of the dyestuff which is the 1:2 chromium complex of equimolecular proportions of 1-o-t0lyl-3-methyl-4-[2'- hydroxy-5 -nitrophenylazo]-5 -pyrazolone and 2- acryloylamino- 7-2hydroxy-5-nitrophenylazo]-8-naphthol-6- sulphonic acid, 6 g./l. of a commercial sodium alginate known as Manutex RS and 40 g./1. of a mixture of 21 parts by weight of a condensate of nonylphenol with ethylene oxide, 5 1 parts by weight of a condensate of nonylphenol with ethylene oxide, 51 parts by weight of sodium dodecylbenzenesulphonate and 27 parts by weight of water, using the subatmospheric pressure procedure described in Example 1 with the modification that after th e serge has been passed 'tfiough a padding mangle it is exposed to saturated steam at 102 C. for 20 minutes prior to soaping off the unfixed dye. The serge is found to be dyed more strongly than similar samples of serge dyed by a conventional pad-steam process (l.e., without t e use of vacuum), and microscopic examination of the dyeings shows a superior penetration of the wool fibers, particularly the hydrophobic parts thereof, in the case of the material treated by the method of the invention.

We claim:

1. A method for dyeing hydrophobic fibrous material by impregnating said hydrophobic fibrous material with an aqueous dye liquor, comprising the steps of (1) subjecting the hydrophobic fibrous material to subatmospheric pressure, (2) bringing the aqueous dye liquor and the hydrophobic fibrous material so subjected into mutual contact, (3) simultaneously with performing step (2), or immediately thereafter, restoring pressure on the hydrophobic fibrous material to atmospheric pressure and (4) bringing about fixation under atmospheric pressure upon said hydrophobic fibrous material of the dyestuff contained in the liquor taken up by said material.

2. A method as claimed in claim 1, wherein the fibrous material is enclosed within an evacuable zone where it is subjected to the subatmospheric pressure, and the aqueous dye liquor is admitted to that zone after evacuation has taken place.

3. A method as claimed in claim 1, wherein a length of fibrous material is subjected to the steps of (l) causing the length of fibrous material to move progressively through a first zone in which it is subjected to the subatmospheric pressure and then through a second zone in which it is impregnated with the aqueous dye liquor, the two zones being separated by a suitable form of seal through which the evacuated fibrous material passes and is thereby prevented from coming into contact with the atmosphere, and (2) allowing the fibrous material to regain atmospheric pressure.

4. A method as claimed in claim 3, wherein the fibrous material is allowed to regain atmospheric pressure on entering the impregnation zone.

5. A method as claimed in claim 3, wherein the fibrous material is allowed to regain atmospheric pressure immediately after leaving the impregnation zone.

Disclaimer 3,644,137.Mawiee Rayner F000, Neil David Stewart, and Alfred Peter Manchester, England. METHOD OF APPLYING PROC- Loelcett ESSIN G LIQUORS TO TEXTILE MATERIALS AND APPA- RATUS THEREFOR. Patent dated Feb. 22, 1972. Disclaimer filed Aug. 19, 197 4, by the assignee, I mperial Uhemieal lmiustfies Limited.

Hereby enters this disclaimer to all claims of said patent.

[Oyfiez'al Gazette JW 10, 1.975. 

2. A method as claimed in claim 1, wherein the fibrous material is enclosed within an evacuable zone where it is subjected to the subatmospheric pressure, and the aqueous dye liquor is admitted to that zone after evacuation has taken place.
 3. A method as claimed in claim 1, wherein a length of fibrous material is subjected to the steps of (1) causing the length of fibrous material to move progressively through a first zone in which it is subJected to the subatmospheric pressure and then through a second zone in which it is impregnated with the aqueous dye liquor, the two zones being separated by a suitable form of seal through which the evacuated fibrous material passes and is thereby prevented from coming into contact with the atmosphere, and (2) allowing the fibrous material to regain atmospheric pressure.
 4. A method as claimed in claim 3, wherein the fibrous material is allowed to regain atmospheric pressure on entering the impregnation zone.
 5. A method as claimed in claim 3, wherein the fibrous material is allowed to regain atmospheric pressure immediately after leaving the impregnation zone. 